The Carrying Capacity Analysis Of Axially Compressed Welded Section Steel Members Undergoing Buckling Interaction

With the development of high strength and light weight enclosing structure system, thin-walled members are widely used in the steel structure,which makes the weight-bearing structure becomes lighter.When the width-thickness ratio of the plate is larger than the slenderness limit values,the plate will buckle easier under compression. However,the carrying capacity of the member doesn't lose because of the post-buckling strength of the plate.And it will produce evident economic benefits that using the post-buckling strength of the plate.The effective width method is adopted in considering the post-buckling strength of the web in Chinese code,for example "Code for design of steel structures(GB50017-2003)","Specification for the design of thin-wall steel structures(GB50018-2002)" and "Technical Specification for Steel Structure of Light-Weight Building with Gabled Frames"(CECS 102:2002) which have different regulations and defects in considering the post-buckling strength of the web.In this paper,considering material nonlinearity and initial geometry defects, width-thickness ratio of the flange and web,slenderness ratio of the member and yield strength of the material,the overall stability bearing capacity of welded thin-walled H-section members under axially compression is analyzed by finite element method. The results show that the parameters above all have various effects on the local and general stability of the thin-walled welded axially compressed members.The buckling interaction should be considered and the web's post-buckling strength could be used when doing global analysis on the thin-walled welded axially compressed members.The carrying capacity of the thin-walled welded axially compressed members which calculated by FEM are compared with the results calculated by the Chinese Codes and the Direct Strength Method,respectively.The comparison shows that the results predicted by the Codes of our country are conservative and the Direct Strength Method is accurate to predict the ultimate strength of the thin-walled welded axially compressed members.Based on the finite element nonlinear analysis,a DSM formula is proposed in this article.The comparison between the ultimate strength predicted by the proposed DSM formula and the existing DSM formula prove that the proposed DSM formula is more applicable for the thin-walled welded axially compressed members.